The magnetic controllable capsule endoscope has been widely used commercially in the stomach examination and proved to be very successful. However, the same magnetically controlled capsule endoscope is not currently used to be placed inside the small bowl and colon to perform a routine examination.
To date, there are three types of external magnetic field generation systems to guide magnetic capsule endoscope devices while traveling in a patient's GI track. They are electromagnetic coils, electromagnet and permanent magnet. In order to meet the requirement of providing sufficient driving force, by external magnetic field or external magnetic gradient to move a typical magnetic capsule endoscope throughout a patient's small bowel, the power consumption for electromagnetic coils and electromagnet systems is very large, and the heat dissipation can make these systems even more bulkier and eventually very expensive to build and operate. Additionally, for electromagnetic coils and electromagnet systems, the electromagnetic compatibility (EMC) is also a big challenge, and potential safety issue relating to the electromagnetic field also post some concern.
Comparing to electromagnetic coils, the permanent magnet is a much more clean and efficient way to generate large magnetic field or field gradient. However, the control algorithm of the permanent magnet is much more complex than the electromagnetic coils. The electromagnet has a little bit more flexibility then the permanent magnet, since its strength can be adjusted by the current. However, for the control of the movement of the magnetic capsule, the electromagnet has the same order of the complexity of the permanent magnetic field. And to achieve the same magnetic field or field gradient, the electromagnet will occupy 2-3 times larger space than the permanent magnet. As for the permanent magnet, the sphere shape is the most efficient for the remote field or field gradient generation.
Therefore, magnetic control system to navigate a capsule through a small bowel is needed, the said system should employ an external permanent magnet dipole and easy to use.